Demonstrative Pronouns

هذا is a masculine demonstrative pronoun meaning “this”.ما هذ؟ means “What is this?”. هذا طالبٌ means “This is a student”. هذا is the subject of the sentence but it is not a word that has case.

ذلِكَ is a masculine demonstrative pronoun meaning “that”. As in English, ذلك “that” refers to objects which are more distant or is used in contrast: هذا طالبٌ وذلك مُدَرِّسٌ

هذه and تلك are the feminine equivalents for هذا and ذلك

Whenever any of these four words is followed by a definite noun we have one unit meaning “this noun”. For example هذا الكتابُ means “this book” and ذلك البليدُ means “that moron”. (These are phrases, not sentences. Note that all four demonstratives end in a vowel, so no helping vowel is needed for elision.) Also, be aware that phrases such as هذا الكتابُ do not mean “This is the book” but only “this book”. These phrases often serve as the subject of an equational sentence as in: هذا الطالب جميلٌ “This student is handsome.”

Arabic grammar books often give the meaning of ھٰذا الکتاب as
“This is the book” too!
هذا هو الكتاب is the unambiguous way to say, “This is the book”. Hopefully, the learned author of this site will be able to clarify this point.

The first sentence may be translated thus: ‘During the holidays at the end of this week, I shall travel to San Francisco.’
The second sentence may not have a literal equivalent in my opinion…but a native speaker would be better placed to highlight this issue.